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THE SALIVAR Y GLANDS. 

 EXPERIMENT 1. The Parotid Gland of the Dog. 1 



EXPERIMENT 2. The Parotid Gland of the Rabbit? 



In this experiment pilocarpine was ifijected, and a sample of the saliva 

 collected. The cervical sympathetic was then stimulated ; during the stimula- 

 1 tion the secretion became slower until it stopped ; on its cessation the stimula- 

 tion was also stopped. After a short time the flow began again ; when about 

 three drops had been secreted the sympathetic was again stimulated, and so 

 on, till a second sample of saliva was collected. 



EFFECT OF VARIATIONS IN THE AMOUNT AND QUALITY OF THE BLOOD 

 SUPPLIED TO A GLAND, UPON THE AMOUNT AND PERCENTAGE 

 COMPOSITION OF THE SALIVA SECRETED. 



In order to form a satisfactory theory of the action of secretory 

 nerves, it is of the greatest importance to know how far variations in 

 the amount and character of the blood flowing through the gland affect 

 the amount and character of the saliva. Our information on this point 

 is unfortunately still vague in many respects. 



Certain broad facts can be readily observed by compressing the 

 carotid artery on one side, after tying the carotid artery on the other 

 side, and the subclavian arteries on both. The gland-veins are cut, so 

 that the amount of blood flowing through the gland can be roughly 

 determined; aiid the chorda tympani is stimulated during different 

 degrees of compression of the carotid. 



When the carotid is compressed to a moderate extent, the chorda on 

 stimulation will not cause so much increase in the blood flow through 

 the gland as it otherwise would, but it will nevertheless cause a con- 

 siderable increase, and the blood will issue from the vein of an arterial 

 colour. In such case, according to Heidenhain, 3 the amount of saliva 

 obtained by a given stimulus will be of normal amount. 



1 Heidenhain, Arch. f. d. ges. Physiol., Bonn, 1878. Bd. xvii. S. 31. 



2 Heidenhain, op. cit., S. 40. 



3 Heidenhain (Stud. d. pliysiol. Inst. zu Breslau, Leip/ig, S. 98) appears to refer to an 

 increase of blood flow above that occurring with partially compressed carotid, and not to an 

 increase above the normal blood flow. 



